The present invention relates to a yarn processing system, as well as to an electronic sensor for a yarn feeding device.
In a yarn processing system as known from EP 06 19 262 A and DE 44 14 870A, respectively, the accessory device processing the yarn is a yarn oiler mounted with a carrier means to the inlet side end wall of the housing of the yarn feeding device. The yarn oiler includes a control unit for an electric drive motor driving a treatment element by which an impregnation substance like wax or oil is applied onto the yarn. The rotational speed of the treatment element is related to the rotational speed of a component in the yarn feeding device, and as such indirectly to the yarn speed. Said component is conveying the yarn within the yarn feeding device and is driven by an electric motor and in a controlled fashion. The yarn feeding device is prepared with its control system and its housing design for a functional and structural controlled co-action with the yarn oiler. A cable, preferably with a detachable connector, extends from the control system of the yarn feeding device through and out of the housing of the yarn feeding device to the control unit of the yarn oiler and is transmitting a signal by galvanic conduction, which signal represents the rotational speed in the yarn feeding device. This accordingly necessitates a structural preparation of the yarn feeding device for the co-action with the yarn oiler and excludes the usage per se of the yarn oiler with other yarn feeding devices having no such corresponding preparation. The prerequisites are similar for the other such accessory devices like controlled yarn brakes, slip conveyors or rotational drives for storage bobbins from which the yarn feeding device is pulling off the yarn, because all of said accessory devices also need said rotation speed signal for the co-action with the yarn feeding device. In case that the yarn feeding device is used without the accessory device, the costly preparation of its control system and its housing is superfluous. In addition, the provided galvanic connection for the speed signal transmission might undesirably influence the control of the yarn feeding device in case of a disturbance at the side of the accessory device or along the signal transmission path.
It is a task of the invention to provide a yarn processing system of the kind as disclosed above as well as an electronic sensor which are able to avoid a preparation of the yarn feeding device in terms of its control system and/or its design, in view of a co-action with any kind of such speed depending controlled driven accessory device, and which furthermore allow one to easily use any speed depending driven accessory device at different types of yarn feeding devices, and wherein the danger of a disturbing influence of the accessory device with respect to the control system of the yarn feeding device is avoided.
Since the sensor according to the invention is galvanically separated and independent from the yarn feeding device, it can be used practically for any type of yarn feeding device, even if the yarn feeding device as used has no constructional preparation or adaptation of its control system for a transmission of a speed signal to the exterior. By this the production costs of the yarn feeding device can be reduced. Any type of accessory device of the kind as mentioned above can be combined later with yarn feeding devices already in use. Surprisingly simple, at least an outwardly leaking part of a rotating magnetic field can be detected from the exterior of a yarn feeding device which has an interior component which is rotatably driven by an electric motor in a controlled fashion. Said leaking part of the rotating magnetic field is available at the mounting location of the sensor but is not used at this location for the function of the yarn feeding device. It is only necessary to select the mounting location of the sensor such that the sensor is able to reliably detect the rotation of the magnetic field. On the basis of said leaking part of the magnetic field, the sensor generates a signal representing the rotational speed of the component within the yarn feeding device. Normally, the housings of yarn feeding devices are not sufficient to shield or suppress the leakage of a part of the magnetic field, which leaking part suffices for detection and generation of the speed signal. Sensors detecting the leakage or wasted part of the magnetic field allow expansion of the range of applications for yarn feeding devices and for accessory devices being driven in dependence from the rotational speed of the yarn feeding devices, since thanks to the sensor, such accessory devices can even be applied on yarn feeding devices which per se are not prepared for a speed depending co-action with any accessory devices.
The signal is transmitted to the accessory device from the signal exit port of the sensor, preferably to the control unit of the accessory device. The signal then is used in the accessory device depending on the control routine of the accessory device. In any case it is assured that the speed signal is available when necessary without interfering with the control system or the drive means of the yarn feeding device by a prefabricated and/or disturbance-sensitive galvanic connection. Provided that the sensor is equipped with a signal cable and a detachable connector, the sensor can be combined with any type of accessory device needing said speed signal. Accessory devices may be used with the sensor which already are prepared for a galvanic connection with the control system or the drive means of the yarn feeding device.
The sensor can include its own power supply and is independent from the yarn feeding device, and optionally, also from the accessory device.
The sensor can be supplied with operational power either from the accessory device or independently of the accessory device from a power supply box of the yarn feeding device. Such box is usually equipped with spare connection ports or connection ports thereon can be provided with minimum effort. Furthermore, the sensor may be connected to a completely independent power supply or may be provided with a battery inside such that the sensor remains completely independent from any other power source.
The sensor can be used at least to assist in the control of a yarn impregnation device, e.g., a yarn oiler, which is provided along the yarn path in order to apply an impregnation substance such as oil or wax on the yarn. This impregnation is important for certain yarn qualities in view of a proper processing of the yarn.
The accessory device in one embodiment is a slip conveyor having at least one friction roll driven in dependence from the rotational speed in the yarn feeding device or from the yarn speed. Said slip conveyor either assists in withdrawing the yarn at a withdrawal side from the yarn feeding device or in conveying the yarn at the inlet side towards the yarn feeding device.
The accessory device in another embodiment is a controlled yarn brake, the braking effect of which is variable depending upon the yarn speed. Said controlled yarn brake may be provided at the inlet side and/or at the withdrawal side of the yarn feeding device.
The accessory device using the speed signal of the sensor is a rotational drive of a storage bobbin carrying the yarn for the yarn feeding device. The purpose of said rotational drive is to reduce or eliminate the twist or drill of the yarn normally resulting when pulling off yarn from a stationary storage bobbin. This can be important for high fabric quality when weaving Lurex or band yarns.
The sensor is mounted at its mounting location by the carrier means of the yarn impregnation device, preferably at or close to the inlet side housing end wall of the yarn feeding device. At this location, particularly in the area of the inlet eyelet of the yarn feeding device, e.g. the rotation of the magnetic field of the drive motor is easily detectable by the sensor. The sensor may be integrated per se into the carrier means. Alternatively, the sensor may be designed with its own fixing means, or the carrier means may be provided with a fixing means enabling simple positioning of the sensor.
The speed signal generated in the sensor is transmitted to the control unit of the electric motor of the treatment element of the yarn impregnation device. If the signal exit port of the sensor is permanently connected with the control unit, the sensor so to speak is an integrated part of a structural unit consisting of the yarn impregnation device, the carrier means and the sensor. In case that the signal exit port is releasably connected to the control unit, the sensor also may be selectively used with other types of accessory devices. It then is even possible to connect the yarn impregnation device in a conventional galvanic manner without the sensor to the control system of a yarn feeding device accordingly prepared for the galvanic co-action with the yarn impregnation device. One type of an accessory device may be selectively combined with different yarn feeding devices.
A receiving socket for the sensor is formed at the housing of the yarn feeding device, e.g., an insertion opening, a threaded bore or a hang-in hole. Said receiving socket can readily be formed with tools available at the working location of the yarn processing systems, e.g. in a weaving mill. It is also possible to form a receiving socket like an insertion opening, a bayonet socket, a screw-in socket or the like in the yarn feeding device housing during manufacturing of the yarn feeding device, however, without using any galvanic connection to the control system or the drive means of the yarn feeding device.
The accessory device is located separately and remotely from said yarn feeding device, while the sensor is located at or close to the yarn feeding device. Signal transmission takes place via a cable. This allows positioning of the accessory device arbitrarily at a location where it optimally fulfills its purpose.
The part of the magnetic field used for the speed detection is a leaking out part of a driving, controlling or monitoring magnetic field of the drive motor, i.e., of an electric motor of the yarn feeding device. The rotation of the magnetic field is representing the momentary rotational speed of all components in the yarn feeding device driven by said electric motor, or the rotational speed of the motor itself, or even the momentary yarn speed, respectively.
The sensor for deriving the speed signal detects the rotation of a part of a magnetic field, which part is not used for the function of the yarn feeding device at the mounting location of the sensor. Said magnetic field originates from a permanent magnet belonging to a rotation detector which is integrated into the yarn feeding device. Conventionally, the winding element is defined by an outwardly protruding winding tube and/or a winding disk on the drive shaft and is made of non-magnetic material. The rotation detector integrated into the yarn feeding device (e.g. U.S. Pat. No. 4,715,411) consists of the permanent magnet provided at the winding element, and of a stationarily positioned detecting element like a Hall element. The rotational movement of the magnetic field generated by the permanent magnet during operation of the yarn feeding device is detectable by the sensor even when it is galvanically separated from the control system and the drive means of the yarn feeding device. For said purpose the sensor ought to be situated close to said winding element at the stationary housing of the yarn feeding device.
The sensor is provided with a probe-shaped housing for the pick-up head apt to detect rotating magnetic fields and/or magnetic field variations of rotating magnetic fields without galvanic connection. The housing of the sensor is to be positioned where at least a part of a magnetic field is leaking outwardly to the pick-up head, said part not being used for the function of the yarn feeding device at the mounting location of the sensor. It is possible to provide a fixation means at the sensor. In order to gain a forceful and clear speed signal and to achieve a completely independent operation of the sensor, amplification and evaluation circuitry might be useful if received in the sensor housing.
The sensor easily may be glued to the housing at the mounting location.
The sensor can also be mounted with a fixing band at the housing of the yarn feeding device.
At least one of the existing protrusions or cooling fins of the housing of the yarn feeding device is used to mount the sensor at its mounting location by means of a clamp engaging at said protrusion or cooling fin, respectively.
The speed signal generated by the sensor without a galvanic connection with the control system or the drive means of the yarn feeding device is used in the accessory device to control the movement of a part thereof depending upon the rotational speed in the yarn feeding device. It is possible to control said part permanently or only in predetermined operational phases according to said rotational speed. The part may then be controlled in direct or indirect proportion to the rotational speed. In a yarn impregnation device with a rotating treatment element, the speed signal is used to vary the rotational speed of the treatment element. In a controlled yarn brake said speed signal is used to vary the braking or tensioning effect on the yarn by means of at least one movable braking element. In a drive for a storage bobbin, said speed signal is used to rotate said bobbin according to the rotational speed in the yarn feeding device such that the yarn leaving the bobbin receives only a reduced drill or no drill or twist at all. In a slip conveyor, a slip element is driven accordingly to adjust the slip in the yarn conveying direction corresponding to the momentary yarn speed.